J Korean Soc Emerg Med.  2023 Apr;34(2):166-176.

Clinical predictors of the positive brain magnetic resonance imaging finding in patients with acute altered mental status in the emergency department

• Kim N
• You KM
• Shin J
• Lee HJ

Abstract

Objective
This study aimed to determine the clinical factors associated with positive brain magnetic resonance imaging (MRI) findings in patients presenting to the emergency department (ED) with acute altered mental status (AMS).
Methods
Patients with acute AMS who presented to the ED were retrospectively analyzed from September 2019 to March 2020. Non-traumatic patients with abnormal alert, verbal, pain, unresponsive (AVPU) scale scores and exhibiting acute change in mental status were included in the study. We evaluated the clinical characteristics of patients with acute AMS according to the results of their brain MRI. A multivariable logistic regression model was used to determine the clinical factors associated with positive brain MRI findings.
Results
During the study period, 138 patients underwent brain MRI in the ED, with 36 (26.1%) positive results. A majority of patients with positive brain MRI findings had underlying malignancies, cerebrovascular disease, higher serum total bicarbonate (TCO₂) levels, TCO₂≥22 mmol/L, lower blood urea nitrogen levels, abnormal findings on brain computed tomography and abnormal findings on neurologic examination. In the multivariable analysis, serum TCO₂≥22 mmol/L (odds ratio [OR], 2.12; 95% confidence interval [CI], 1.09-4.12) and the presence of cranial nerve abnormalities (OR, 3.88; 95% CI, 1.55-9.68) and extremity abnormalities (OR, 2.76; 95% CI, 1.11-6.88) were significantly associated with positive brain MRI results.
Conclusion
Serum TCO₂ level and the presence of cranial nerve and extremity abnormalities in the neurologic examinations were significantly associated with positive brain MRI results in patients with acute AMS.

Keyword

Unconsciousness; Magnetic resonance imaging; Diagnosis; Risk factors